1. Field of the Invention
The present invention relates to a correction apparatus which irradiates defective bright points with a laser beam to reduce the number of defective bright points.
2. Description of the Related Art
A liquid crystal panel has an array substrate made of a glass substrate, a color filter substrate made of a glass substrate, and liquid crystal enclosed between these substrates.
In the array substrate, a large number of signal lines and gate lines are arranged in a matrix. At intersecting portions between the signal lines and the gate lines, TFTs (Thin Film Transistors) are provided to discharge electric charges to pixel electrodes. A large number of pixel electrodes each having a size of 100 to 400 μm or so are provided in a matrix, respectively neighboring the TFTs. In the color filter substrate, a coloring layer, a protection film, and a transparent conductive film are formed. A polarizing filter is provided in the surface of each glass substrate. When a liquid crystal panel is shipped as a commercial product, a protection film is provided on the surface of the liquid crystal panel.
Meanwhile, if a liquid crystal panel includes a portion where TFTs malfunction or a portion where pixel electrodes have not been formed normally, pixels corresponding to such a defective portion cannot shield light penetration. In this case, these pixels appear as defective bright points.
According to a method of correcting a defective bright point, defective bright points are reduced. More specifically, defective bright points are reduced by cutting a wire on a substrate or by melting a metal layer.
To correct thus a defective portion in a process object which is a target to be processed, a laser is used. A technique of this kind is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publications No. 7-124764, No. 11-90659, and No. 2005-33007.
In order to reduce defective bright points by irradiation of a laser beam as described above, a laser beam of a predetermined intensity needs to reach a defective bright point. However, a laser beam irradiated from a laser output section is polarized by a polarizing filter so that the intensity thereof is weakened. Further, some liquid crystal panels may include flaws in their protection films. These flaws or the like influence a laser beam to scatter on the protection films.
Only a part of the laser beam outputted from the laser output section as described above reaches a defective bright point. That is, an intensity ratio of such a part of a laser beam that actually reaches a defective bright point to the laser beam outputted from a laser output section varies depending on individual liquid crystal panels.
A success rate hence lowers in case of correcting a defective bright point with an output thereof kept constant by a laser output section. Besides, work efficiency deteriorates since laser irradiation is repeated until a defective bright point is corrected while observing this point.